Can I suggest a few more shop links?
Pete Bland Sports in Kendal. Good selection of tarmac shoes but loads of choice for XC / trail running, with specialist fell running shoes too. Offer mail order.
Bourne Sports. Only a few miles from OCuk. Long standing independant sports shop. Have an official shop run every Saturday morning with promo's. Treadmill instore which they are more than happy for you to test shoes on. No rush service during the week - my last purchase saw me try on over 10 pairs.
No association with either shop except as a satisified customer.
Sub-4. Only visited briefly a couple of times but very specialist running shop in Stoke-on-Trent. Offer all manner of assessments - IIRC they have a running track in their premises which has video cameras embedded in it. Cost for the longer assessments can be £200+.
Joe Jogger. Mail order only, so only good for people who know what trainer they want (ie a second or spare pair) but discounted prices.